Conventionally, a machine tool controls a position and orientation of a tool with respect to a workpiece by operating one or both of the tool that actually performs machining on the workpiece and a table on which the workpiece is placed, in accordance with a machining program for machining the workpiece.
Specifically, the machine tool includes five or more axes including three mutually orthogonal axes for performing translational movement, a rotation axis of the tool, and a rotation axis of the table, and controls the position and orientation of the tool with respect to the workpiece by operating each axis in accordance with control by a numerical control device based on the machining program. Operation of the axes is translation or rotation. By controlling, the machine tool machines the workpiece in accordance with the machining program.
When the machining program includes a command for simultaneously operating five or more axes in the machine tool, if the numerical control device cannot simultaneously control operation of the five or more axes, the numerical control device cannot operate each axis in accordance with the command. For that reason, conventionally, in a case where a numerical control device that cannot simultaneously control operation of five or more axes controls the machine tool, when the position and orientation are controlled of the tool with respect to the workpiece, the tool is once separated from the workpiece, and the tool is brought close to the workpiece after the orientation of the tool is changed (for example, see Patent Literature 1).